Sorry for the hiatus. Things have been a bit crazy. The shiur and sources are available: here.
In this shiur I spoke about the role that Kabbalah plays in the Halachic process. This question can be asked on several levels, but I focused primarily on the role of the Zohar and the Arizal in psak. [One can also speak about the role of dreams, bas kols, etc.]
There are two extremes: 1) The view of the Chasam Sofer, that is traditional in many Ashkenazi circles, that Kabbalistic material does not affect Halacha. He pithily calls any psak based on a synthesis Kilayim. 2) The view often cited of the Masas Binyamin, that the Zohar outweighs all post-Talmudic authorities combined. The Ben Ish Chai and Chida, as well as many poskim of various Edot HaMizrach have similar sentiments about the Arizal. One can in theory accept only one of these authorities in this way. On the one hand, one can accept the Zohar and not the Ari in this way, if one assumes that the Zohar is a Tanaaitic work. On the other hand, this may weaken his position, as R. Shimon Bar Yochai was not usually accepted in the Talmud, so there is not reason to accept the positions written in the Zohar. On the other hand, the Arizal is not ascribed to a Tanna, but that may give him the upper hand, and his rulings were issued with knowledge of the previous sources, both Kabbalistic and Halachic.
To cite a few views that fall somewhere in between:
R. Eliyahu Mizrachi says that we cannot force anyone to follow Kabbalah because it is meant to be esoteric. Radbaz writes that we don’t follow Kabbalah if it contradicts Halacha, but if it offers a chumra, we should follow it. This position is accepted by Beit Yosef and Mishna Berurah. R. Yaakov Emden adds that if the Gemara is unclear, we can interpret the Gemara in light of the Zohar. R. Menachem Azaryah of Fano adds that we should try to find a way to fit the Zohar into the Gemara. The Beit Yosef uses this type of argument to rule in favor of those who think we should not wear tefillin on Chol HaMoed.
As Gush was having a Yom Iyun on R. Ovadiah, I spoke a bit about his approach. In general, he fought back against the mesorah of the Chidah and Ben Ish Chai, and rule in a more “Ashkenazi” manner, rejecting the authority of the Arizal. However, this was partially a function of his desire to create a pan-sfardi psak that followed the Beit Yosef. However, his desire for unity among Sfardim seemed to override his conviction that Sfardim must always follow the Beit Yosef, so in some cases, where the minhag was too strong, he found Halachic ways of justifying the Kabbalistic minhag (as in the case of the Hanoten LaYaef Koach). For more on this, see the discussion in R. Beni Lau’s book.
This topic has been discussed many times in many contexts, and they can be seen in the sources I provided, and well as the sources I added for further reading. I especially encourage people to read Jacob Katz and Beni Lau’s works on the topic.